text:
Why UA954 was diverted to Houston IAH on 25th Feb?
Fligth UA954 on 25th February was diverted to IAH when in flight from SFO to TLV.
Passengers were updated and told that the plane had a technical issue that was preventing it from crossing the ocean.
According to flightaware the plane was close to the border between Wyoming and Montana. It continued flying and landed in IAH.
What was the reason for the flight not being able to continue flight over the ocean, but still allowing it to continue flying safely for around 4 hours?

Are you asking about this particular flight or in general?  If the latter, then it's too broad.  It would be a long (and incomplete) list of reasons.

Sounds like something to do with ETOPS (not crossing the ocean) and putting the passengers on another flight (diverting to IAH).

@mins, and likely either have a spare plane there or at least enough other flights to rebook the passengers to.

They told ATC they had an unknown odor in the cockpit. When ATC asked for more detail they said they had narrowed it down to the cockpit heating element. They specifically said they were not declaring an emergency.
It just happened to have occurred while they were within range of the LiveATC receiver so the transaction is on the recording (normally you can only hear ATC on the en route feeds). The recording is here. After ATC tries to raise them several times they check in at about 17:22 on the recording and tell ATC about the odor and need to divert. About 5 min later, I presume after conferring with the company, they tell ATC they are not declaring emergency but they're diverting to IAH. When asked for further details the say it's the cockpit heating element. After a few more exchanges with ATC they fly out of range of the LiveATC receiver.
Here's my transcript.

Times are per the recording (MM:SS). The recording starts at 0630Z so add that to the times listed for UTC
16:15 [ATC] United 954 change to my frequency if you're not there, 127.75
16:28 [ATC] United 954 Salt Lake
16:38 [ATC] United 954 Salt Lake Center
17:10 [ATC] United 954 Salt Lake Center
17:23 [UA954] Salt Lake united 954 checking in 350
17:27 [ATC] United 954 Salt Lake Center, roger. Welcome
17:30 [UA954] Yeah, it looks like we've got some unknown odor in the airplane. Were gonna - were either gonna go to Houston or San Fran. I'll get right back with you.
17:40 [ATC] United 954 thank you
21:54 [UA954] Salt Lake 954
22:13 [UA954] Salt Lake 954
22:16 [ATC] 954 go ahead
22:20 [UA954] Yeah, we are not, I repeat, not declaring emergency. We just need to turn to Houston for an unknown odor in the cockpit.
22:27 [ATC] United 954 roger, clear to Houston airport via direct. Maintain FL350
22:36 [UA954] Ok, 350 direct to houston, thank you. United 954
22:52 [ATC] United 954 I just want to confirm that's India Alfa Hotel. Is that what you're showing?
22:57 [UA954] India Alfa Hotel, affirmative
23:00 [ATC] 954 roger, thanks
23:07 [ATC] United 954 they're gonna want to know maybe a little bit more details. Is there something else maybe you can tell me about the odor so I can pass that along?
23:17 [UA954] Stand by
23:23 [UA954] Yeah, we've narrowed it down to the cockpit heating element is, we believe, the source of the smell. But that's the best we can deduce at this point.
23:34 [ATC] United 954 roger, thank you.
There are a few further routing exchanges before 954 flies out of range.

Do you happen to have ATC transcript or anything for that?

@vasin1987 I'll add a link to the LiveATC recording

So the times listed are MM:SS into the recording you linked to, not HH:MM, correct? That makes the first line at 06:46:15Z, right? took a while to figure out why UA954 took an hour to respond to ATC...

Oh, sorry. Yes, the recording is 30 min. Long, so its minutes:seconds. I'm trying to figure out why the colons didn't copy with the rest of the text. Very weird.

@FreeMan do the colons make it less ambiguous or do I need to add 00:16:15, etc.?

Oh, and at 19:21 in the recording does ATC tell the other plane to go direct to vagina?

Or maybe he's saying "Regina."

@TomMcW it does make sense (even without the colons), it just took a while for that to sink in, and I wanted to confirm I was on the right track.

I just proposed an "(MM:SS)" in the heading. I think it makes it a bit clearer. Hope you don't mind. Btw: this is one of the reasons I could never fly outside Germany: I listened to the radio and understood very little and had to rewind a few times. The transcript is amazing.

@PerlDuck I'm listening to EHAM ATC right now and I can't understand a thing they're saying. I'm lucky to catch the last two digits of the ID. :)

As mins linked in comments, the flight diverted due to a smell of smoke. Diverting to Houston was likely done to get better maintenance facilities or for availability of a replacement aircraft if needed. Houston also left them closer to Tel Aviv (11.5 hours) than returning to San Francisco (13-13.5 hours). Houston is United's second largest hub behind Chicago, and O'Hare is much busier and doesn't appear to have 787 service with United.
The flight had been in the air for about 1.5 hours when they diverted. It took 3.5 hours to divert, but it would have taken 11.5 hours to reach Tel Aviv. Even if the pilots thought they had narrowed down the cause, it's safer to divert. Fires in flight can spread rapidly.
If the conditions had worsened during the diversion, there would have been closer airports to divert to than if they had continued over the North Atlantic. It's possible that ETOPS rules also prevented them from crossing the Atlantic.


text:
What does it mean when your destination airport is currently "below IFR minimums"?
Does it mean that absolutely nobody can land there until conditions improve? Can ATC still give you an IFR clearance to your destination airport in this case?

@Notts90 I don't understand this comment - airports absolute do get closed or at least stop receiving traffic. If the airport can't cater for the IFR minimums required then nobody lands there - simple.

@Dan It's not that simple. I've landed many times, legally, in Part 91 operations when the airport was below minimums. Whether an airport is below minimums is determined by what instruments on the ground are reporting, not what the pilot sees. Under Part 91 you are allowed to fly an approach regardless of what those instruments are reporting. Whether you can legally land or not depends on what you see when you reach the MDA or DH, and you can often see approach lighting even though the airport is below minimums. This is especially true at night.

@Terry No doubt, maybe I've misread but I interpreted Notts comment as surprise that there may be times where no landings are possible.

@Dan I will try and be clearer next time as that’s not what I meant. I know an airport can be shut. The way I read the question was as if it was implying an airport was permanently below IFR minimums and therefore no one could ever land there.

@Notts90 Gotchya!

It would be very helpful to know where you read or heard the phrase, to get some context. But, it likely means that weather conditions at the airport are below the IFR takeoff minimums in 14 CFR 91.175:

(f) Civil airport takeoff minimums. This paragraph applies to persons
  operating an aircraft under part 121, 125, 129, or 135 of this
  chapter.
(1) Unless otherwise authorized by the FAA, no pilot may takeoff from
  a civil airport under IFR unless the weather conditions at time of
  takeoff are at or above the weather minimums for IFR takeoff
  prescribed for that airport under part 97 of this chapter.
(2) If takeoff weather minimums are not prescribed under part 97 of
  this chapter for a particular airport, the following weather minimums
  apply to takeoffs under IFR:
(i) For aircraft, other than helicopters, having two engines or less—1
  statute mile visibility.
(ii) For aircraft having more than two engines— 1⁄2 statute mile
  visibility.
(iii) For helicopters— 1⁄2 statute mile visibility.

Landing minimums are per-approach so it wouldn't make sense to say that the whole airport is below IFR minimums based on landing criteria. However, without reading or hearing the phrase in context, I may be wrong.
As for landing there anyway, even in zero visibility a private pilot operating under part 91 is free to take off, or to start an instrument approach. You can't legally land if visibility is below the approach requirements, but you can still fly the approach to 'take a look'. It might not always be smart, but it's legal.
On the other hand, commercial flights under part 135 or 121 can't even start an approach unless conditions are above certain minimums (e.g. see 135.225(a)). Those minimums are usually just the ones required for the particular approach, but they can also have operator-specific requirements. Of course, many commercial aircraft have crew and technical capabilities that light aircraft don't (like shooting a CAT III ILS), so they might still have a better chance of landing in marginal conditions.

Take-off minima of a destination airport don't seem particularly relevant, so I am inclined to think it simply means it is below minima of its best approach. I agree it would deserve clarification.

There is additional complication that even if there is, say, CAT III approach, it can only be used as CAT III if the plane is certified for it and the crew is current, which is far from granted even for airline flights.

I think they are referring to the minimum visibility and ceiling that is required. There are two cases. Actually landing at an airport and filing an IFR flight plan.
Per §91.175   Takeoff and landing under IFR.

(c) Operation below DA/DH or MDA. Except as provided in §91.176 of
  this chapter, where a DA/DH or MDA is applicable, no pilot may operate
  an aircraft, except a military aircraft of the United States, below
  the authorized MDA or continue an approach below the authorized DA/DH
  unless—
(2) The flight visibility is not less than the visibility prescribed
  in the standard instrument approach being used; and

Part 91 aircraft may attempt an approach if visibility is reported to be below minimums, but Part 121 and 135 may not begin the approach if reported visibility is below minimums. Effectively, the airport is closed to them.
You may file to an airport that is expected to be below minimums at the time of arrival, but you must file an alternate that is above IFR minimums. §91.169   IFR flight plan: Information required. has details.

(c) IFR alternate airport weather minima. Unless otherwise authorized
  by the Administrator, no person may include an alternate airport in an
  IFR flight plan unless appropriate weather reports or weather
  forecasts, or a combination of them, indicate that, at the estimated
  time of arrival at the alternate airport, the ceiling and visibility
  at that airport will be at or above the following weather minima:
(A) For a precision approach procedure. Ceiling 600 feet and
  visibility 2 statute miles.
(B) For a nonprecision approach procedure. Ceiling 800 feet and
  visibility 2 statute miles.

So yes, ATC can give you a clearance to an airport that is below IFR minimums.

You can still get clearance to the destination, at your discretion. It's not unheard of for weather conditions to be below minimums now and quite acceptable a few hours later after all.
Think Milan Linate, an airport plagued by early morning fog. A flight taking off from say Amsterdam to Milan may take off with the airport covered in dense fog that would make it impossible to land legally, and by the time it gets there it's a clear morning with no fog or clouds.
Of course as always you, the pilot, are responsible for your actions and if you take off knowing your destination is currently closed for you you'd better have a viable alternate plotted just in case the expected improvement in conditions doesn't happen.

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sort: votes


text:
What is the "Centre of Pressure"?
This question may sound naive but surprisingly it puzzles me.
A wing has a centre of pressure, does it mean that lift acts on point and not on the whole chord of an airfoil?

Your body has a centre of gravity. Does that mean that gravity act only on your centre and not on your limbs and head?

Aerodynamic force (part of which is Lift) is nothing more than the sum of all the individual aerodynamic forces acting on the surface of the airframe. At each and every tiny little square micrometer of the aircraft surface, the air is pushing on the airframe. It is pushing with some force equal to the normal air pressure at that point, ($lbs /inch^2)$ times the surface area of that tiny section. All these tiny aerodynamic forces push on the aircraft surface in a direction normal (perpendicular) to the surface.
To make things simpler (for calculations and explanations), engineers, and flight instructors, artificially sum all of these tiny individual forces into one total force. This is done by adding (vectorially) all the individual forces up into a single total force vector, which, if it was the only force acting on the airframe, would, theoretically, create exactly the same total force and rotational moment that all the tiny little real forces actually produce.
This total artificial force is then broken up, again artificially, into two components, one that is normal (perpendicular) to the flight path vector of the aircraft (This is what we call Lift), and one which is parallel to the flight path (This is what we call Drag). They both can be considered to act through the same point that the total force vector was calculated to act through.
The point that this total artificial force is considered to act through is called the Center of Pressure.
What's it for? This is the point in the airframe, where,. if it was locked down at that point, the aerodynamic forces would be balanced around it and would produce no rotational moment. i.e., like putting a pin through an arrow, or the weathervane on your roof, if the pin through the arrow, or the axis of the weathervane went through the center of pressure, then the wind hitting the vane would not cause a rotational moment and the weathervane would not spin and align with the wind. It would just sit there, because the force (actually, the moment) on one side of the Center of pressure would be equal to the moment from forces on the other side and they would cancel each other out.
Why is this important? because in free flight, there is no pin, or axis attached to something immovable. An aircraft is free to move unconstrained. When an aerodynamic force is applied to a body which is free to move unconstrained it will rotate about it's center of Gravity. So if the Center of Pressure is not co-located with the center of gravity, (which it hardly ever is, exactly) then any aerodynamic force on the body will generate a rotational moment (a torque) about the CG.

Center of pressure is not a point "where the lift is most concentrated". Center of pressure has very little relation to how is lift distributed along the wing (you can have exactly same centre of pressure for infinite number of different distributions of lift).
The center of pressure is mathematical sum of all local pressure vectors along whole wing surface. But it is only, more-or-less, thought summing, this point has no special meaning in terms of stress distribution or so (at least no straightforward one).
You could as well continue to put all local pressure points into equation of movement and you would get exactly the same result. But equations with plenty small force vectors would be unnecessary complicated and if you do no need this level of complexity, it is easier to sum all forces in advance and use the summed value instead.
Note that if you would want, say, for example, calculate stresses inside the wing, you can not do like this. You would be forced to put each local pressure point into the analysis. But as long as you could assume whole wing to be solid (which is usually acceptable approximation for lot of simple problems), using single summed lift vector is easier.
If you simply sum all fractional pressure vectors, you get total vector of aerodynamic force. Which is enough to know how big force and in which direction acts on the airplane. But in order to be able to analyze rotational effects, you need to know in which point this total force acts (because same force vector shifted into different point of solid body will cause different rotation). And this is where center of pressure comes into the play, as it is the point where thought summed aerodynamic force should act in order to affect airplane (as a whole) by same translational and rotational effects as actual pressure distribution along the wing does.

You are correct, Lift does act on the airfoil not through one specific point.  The CP is the average point, through which the total forces (=sum of unbalanced surface pressure) of the aerofoil act. It is used to illustrate and simplify common concepts.

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text:
Can air-superiority radar function as weather radar?
Can the big, fat, sophisticated air-superiority radar in a modern fighter aircraft's nose serve as a weather radar for navigation in stormy conditions?
Alternatively would a datalink from somebody else (perhaps a tanker assigned to the deployment flight) be used to provide weather radar imagery into the cockpit?

It is possible that fire control radars do have weather modes built into the LRUs; I'm not sure, though.

@CarloFelicione -- it wouldn't surprise me if they did as it's sort of an obvious function to add (if you're a pilot that is ;) but I don't know either :)

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text:
What are these vertical slats under the wings of the Be-200?
This is a photo of the Be-200, an amphibious aircraft, taking from a youtube video.

I would like to know what are all those vertical slats underneath the wings? What is their purpose? To me they seem to add unnecessary drag.
Note, I'm not talking about the little pontoons at the ends of the wing. Between the pontoons and the hull are a bunch of vertical protusions that remind me of wing fences.

Looking at the pictures on Wikipedia, it looks like they are just fairing covers for the flap extension system.

They are flap track fairings, which contain the flap mechanism. They've already been discussed elsewhere on this site. You can also see them in this photo.

Image from airvectors.net
They actually reduce the drag by enclosing the flap mechanism.

So they are also anti-shock bodies? They look radically different from the linked question you provided.

@DrZ214 In this particular case, I don't think they serve that purpose, instead acting only as a cover for the flap mechanism.

I suppose the question was more about the object on the outer wing, most likely to float on the water and prevent the wing tip from touching the water during landing or takeoff

If you are talking about the pods on the outer wing, they are "underwing stabiliser floats" (wikipedia).

The underwing stabiliser floats fitted on wings provide stability in water. (from naval-technology)

I think they also prevent the wing tip to touch the water while landing. Also, it is common in Aircraft design to put weight near the tip of the wing to reduce the root bending moment (from another forum for example)

The last sentence of the OP's post says that they are specifically not talking about the pods on the outer wing.

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text:
What is this metal plate below the door?
What is this metal plate for?

(source)
You can also see it here:

(source)
Is found on many aircraft so what is that piece of metal right there?

The entire hull is metal. Though I would guess for aiming the stairs

Or a strengthened area to avoid damage to the fuselage due to stairs moving around.

And/or an access panel to get to the inner workings of the door?

Greg is right. You can see from the damaged paint below the door on the first image that this area gets more abuse than the rest. It needs some protection. There is more on the inside, because the corners of the door cutout accumulate stress when the fuselage is pressurized. That is also the reason for the massive door locks - most of the stress is transferred into the door.

@Greg is correct. It is a scuff plate, to protect the fuselage from damage due to GSE (like jetbridge etc). The image below shows it.

Image from slideshare.net
The image below shows an example made out of Ti from a manufacturer's site.

Image from exoticmetals.com


text:
What is this protrusion on the door?
There's something below the door on almost every commercial aircraft. What is inside that box? The protrusion can be seen from the interior of the aircraft.
Source

On Youtube: Emergency slide deployment on British Airways 747-400. The trick is that the slide is fixed to the cabin floor and the container is on the door. On some planes, the door slides upwards. The slide must be separated from the floor before the door is opened for normal use. Voice orders from the purser to arm and "disarm" (don't know the word in English) slides can be heard on the cabin public address.

@mins i always hear cabin crew instruction "arm the cabin door&cross check" and "disarm cabin door&cross check" in English everytime I fly. Then they may proceed to announcement in local language. Source:experience of flying in southeast asia.

The copyright on the page for the image is pretty clear that it's not permitted to be reposted here: This photo is copyright protected and may not be used in any way without proper permission.. They further go on to say _ You may not use these photos on any web page, commercial or non-commercial, for profit or non-profit, without written permission from the photographer. Contact the ASN staff to request permission_

@kepler22b - Wikipedia is a good place to find images that are licensed for sharing (generally either public domain or CC license), here's one that even has a caption that says what that box on the door is, here's another

It contains the evacuation slide. From airspacemag:

An escape slide sits inside a carbon fiber pressure cap covered by a casing of material similar to the aircraft interior walls—that big square box at the bottom of an airliner’s interior door.

Here's an image from Boeing:

Image from Boeing.com
According to Boeing, the positioning of evacuation slides inside the doors reduced the deployment time.

By 1963, improvements in materials and inflation systems reduced the weight and bulk of the slide system, making it practical to move the slides out of the ceiling to the lower inboard face of the cabin doors (see fig. A). This location resulted in a still more efficient escape system, reducing the time needed to ready an escape slide from between 20 to 50 seconds to between 18 and 24 seconds, including door opening time.


text:
What is this device protruding from the rear of this 787?
While looking at the photos from this question
I noticed a small protrusion from the side of the plane. You can see it in the photo:

and in the diagram from l@aeroalias answer:

In the diagram it appears to have something to do with the apu or is fire protection system. There's a shaded line running to it.
What is this object?

Edit: It does look like an antenna. I found a diagram of 777 antenna placement here, but it doesn't show anything in that area.

Some of those lines don't seem to point to what they're labeled. APU Compartment Firewall, Inlet Door, etc.

@egid Yeah. Aeroalias noted that on the other question.

Since its possibly part of the fire suppression system, maybe an air intake for the AFFF system, although I don't know why it would be shaped like that, maybe because of the boundary layer problem in flight wouldn't allow it to suck in enough air to generate foam...

It looks an awful lot like a standard blade antenna, maybe for TCAS? Not sure if it has a twin on the other side.

@mins Thanks. Fixed it

@mins huh. Interesting.

A drain port for the APU?

I agree it looks like a VHF or similar antenna too, though I haven't been able to find a diagram of antenna placements for the 787.

Yes, looks like a drain mast to me.

@Porcupine911 Hadn't thought of that.  Good suggestion, except I've found several sites that indicate that the 787 doesn't have a drain mast. They opted for a grey water tank instead.

@TomMcW, I was thinking of a drain from something else. The 787 still has drains to remove any pooled fuel, oil, water, de-ice fluid, etc.

As you have already imagined, it's the APU fuel line shroud drain, as visible here:

(Source)
Detail:

The fin gives an aerodynamic profile to the drain. The reason this drain exists seems to be:

Natural fuel leaks from the auxiliary power unit (APU) fueling line
  were supposed to drain harmlessly out the bottom of the structure as
  designed, though rather than do that, the fuel was pooling into the
  APU exhaust cone.

(Source)

Seems to be a lot of drag causing surface area for a drain line. I'm surprised that the fin extends so far from the surface and is so "deep" (fore to aft).

@FreeMan If the drain is too close to the surface, leaked fuel and oil will flow along the fuselage with the airflow, eventually reaching the hot exhaust and ignite.

@user71659 ah, that makes sense!

What do they mean by "natural fuel leaks"?

@user71659, Indeed.  If the fuel leakage took place within the boundary layer, it would "fall" back and stick to the fuselage, hence the need for such lengthy fin.


text:
What is this in the window?
Every time I have flown and sat in a window seat, I have noticed this small tube at the base of the window.

It looks like it might be either metal or a small air pocket, but I'm not sure. I've been seeing it for years and always wondered what it is.
What is this "tube" embedded into airline windows, and does it have any purpose?

It's a hole in the middle of the three window panes to equalise pressure in the gaps between the planes.

As pressurized aircraft's windows exist of several layers (usually three) there's this little hole to compensate differences in the pressure between inside and outside the aircraft.
Inside the aircraft the pressure is much higher than outside so without this little hole the windowd layers would be pushed together and break.

"without this little hole the window layers would be pushed together and break": Do you mean pushed in the same outside direction? If so why would they break? They are supposed to be able to individually bear the full pressure differential.


text:
Are there any real life instances of aircraft aborting a takeoff or landing to avoid a vehicle?
I came across a fake video of an A380 closely avoiding a fuel truck. More details at Snopes including a link to the YouTube video.
While this video is not real, I'm interested in finding out if it's a realistic situation and if there are any real instances where accidents have been avoided because crew decided to abort takeoff or landing as a result of an unexpected runway intrusion as seen in the video.

Not a vehicle, but I've aborted landings because of deer or cows on the runway.

Do you mean intentional intrusions to cause a crash with an airplane or just any kind of intrusion?

What surprises me is that anyone thought that video was real.  I mean, GTA V's graphics are decent for a video game at the time, but they're not that good.  My first thought seeing the video was "low quality CGI reenactment", no way that looks like actual video footage.  How would such footage even exist?  If there was a terrorist attack of that sort, I doubt there'd be someone perfectly following it with a camera to get those angles...

@DarrelHoffman, Social media and common sense does not always go together. People believe anything coming in either shared or forwarded.

Too far off what was asked to be an answer, but in 2017 an Air Canada flight almost tried to land on a taxiway with four full planes waiting for takeoff, missing one of them by less than 5 metres https://en.wikipedia.org/wiki/Air_Canada_Flight_759

I mean, to the extent that an airplane counts as a 'vehicle,' this is a relatively common occurrence.

@llama Even less far off, an Air Canada Jazz plane did land on a runway with 2 snow removal trucks on it, also in 2017.

@jamesqf In the late 80's, early 90's I used to do a lot of bush-piloting in single-seaters to remote small air-strips in Northern Scandinavia. My personal list: 3x sheep, 2x cow, 4x reindeer, 1x a herd of ponies, 2x moose, 1x guy mowing the grass of the runway and once in Finland I didn't get a good a look at it, but it looked to me like a young bear or maybe a wolverine.

@Tonny: You've got me beat, especially if the reindeer were pulling a sleigh :-)

@jamesqf Does getting a reindeer sleigh-ride from the airstrip to a nearby hotel count?

Wait, those incursions happened this century?  Aviation needs to start using super-new railroad tech to positively interlock moves like that... (there's a bed of horizontal rods that interock/prevent improper movement)  "Is he not clear, that Pan American?" "No, runway lights are still blue".  tink as the runway occupancy detector releases an interlock "Clear of runway, Clipper 1736" Cha-thomp clank thomp "Ah, runway lights are green" "KLM clear for takeoff".

There is a famous case of someone intentionally parking a van on a runway to prevent an aircraft from landing.  A piper cub crashed into it.  A lawsuit against piper ensued, saying that the airplane design was defective, due to inaquate visibility.  Not quite within the scope of your question though

Not only is it possible but it happens. This is formally called a "runway incursion" and it does happen like 2005 Logan Airport runway incursion or the B733 / vehicle, Amsterdam Netherlands, 2010. Skybrary has a full list you can find here which is quite lengthy and includes a full section for Vehicle Incursion.

Also, obligatory AVHerald link: https://avherald.com/h?search_term=incursion&opt=0&dosearch=1&search.x=0&search.y=0

In 1978 a B737 aborted a landing due to a snow plow on the runway. The aircraft crashed during the go around because one thrust reverser did not stow properly.
https://en.wikipedia.org/wiki/Pacific_Western_Airlines_Flight_314

Yes. I was on final once when a taildragger in front of suddenly turned around to backtaxi and turn off on the taxiway he had just passed, thinking to do me a favor and get off the runway quicker.  Unfortunately, I had been catching up to him on final anyway, so I just powered up and went around.

Why to call that pure taildragger so shamefully, "a vehicle" ...

Motor vehicle with a wing, same as mine. Just happens to be 10-20 years older! And mine is 46 years old.

I aborted a landing at Lake Tahoe once because there was a snow plow on the runway. I guess the guy didn't have a radio or wasn't paying attention to it.

If you don't quite abort...
Plane Collides with SUV While Landing at (Texas) Northwest Regional Airport (52F)

I can remember one evening quite some years ago  when there was a sudden extremely loud noise. Not quite an explosion -- much too protracted and no shock, but you get the general idea. Since there was no flying debris, no visible columns of smoke, no sign of anything else out of the ordinary, I ignored it apart from paying more attention to the news that evening.
The news reported that Concorde had aborted a landing at Heathrow because somebody had strayed onto its runway. This required afterburners! The emergency services lines closer to Heathrow were jammed for quite some time, with people trying to report the "explosion".

I personally witnessed one at EWR (Newark International). The runways in EWR run parallel to New Jersey Turnpike, only meters away.  I was driving on NJ Turnpike northbound when a flight (looked like a B737, but I'm not sure) touched down parallel to the I-95 just at my level and moments later powered up and went around. A few more moments later I noticed another, much smaller, plane further along the same runway. This was in 1998 or 1999.

"Only meters away" — about 500 of them.

@hobbs it certainly feels a lot closer when you drive along the highway and a large aircraft is landing along you.

Yes, I know :) I do it pretty often. Feels like there's about to be a Turnpike Incursion every time.

I am but a meager low time private pilot, but I'm sure this happens all the time as it has happened to me. Before I got my certificate, I departed my home (towered) airport solo planning to buzz over to a nearby very small uncontrolled airport and practice some landings. When I arrived, the city mower was working around the runway, apparently not listening to CTAF. I aborted the first landing as he crossed the runway just in front of me.
Fortunately, he was just finishing the area around the runway and I was able to continue practicing without any further issue.
From a safety standpoint, it was never a big deal. I saw the mower, was aware of his location, and watched to see if he would depart the area before I got close to the ground. He didn't, so I performed a go around. I was surprised that he seemed not to notice me, but it was more inconvenient than unsafe.

On my first flight I flew into LAX and we were coming into land and suddenly went up again. Looking out of the window and there was another plane on the runway. The captain confirmed over the intercom that was the reason for the aborted landing. I would guess this was in 1977.


text:
Have you seen gyroscope horizon moving while flying long distances?
I've seen video where a man is telling that pilots flying in aircrafts do not see gyroscope horizon drift while flying long distances.
I know this question might sound idiotic but I'm just curious if you have ever noticed actual gyroscope horizon (mechanical one) moving while flying long distances. If not, are those gyros compensated somehow?
Have you ever recorded that on your camera?

Ignore those idiotic videos.  If the Earth were flat, almost nothing in long distance air travel would work.

See also this Q&A. Particularly the part about corrections in ring laser gyros in this answer

@Simon Not to mention things like Earth orbit...


text:
Where can I find speed and thrust data for airplanes during the approach?
While trying to gather information on fuel consumption during the approach I have found this equation :
$$f=C_{f1}\cdot (1+V_{TAS}/C_{f2})\cdot T$$  (on this FAA paper)

$f$ is the fuel flow
$T$ is the thrust acting parallel to the aircraft velocity vector
$C_{f1}$ and $C_{f2}$ are the first and second thrust-specific fuel consumption coefficient
$V_{TAS}$ is the true air speed

From what I have understood Cf1 and Cf2 are constant and their values can be found (all the documents regarding these issues are 100 pages papers so I have not read everything yet).
I would like to plot the fuel flow for different airspeeds and thrusts. What are the typical values during the approach ?
I would like to have these data for several flights during the last 20 or 25 minutes of the flight.
What I am looking for is exactly what flightaware.com provides except that they use ground speed (an exemple here). How can I convert to TAS ?
Also they don't provide anything on thrust. Do you know where I can find thrust data ?

For what it may be worth, a 747-200 with Pratt & Whitney JT9 engines at flaps 30 degrees, gear down, stabilized on a 3 degree glideslope will show a fuel flow of approximately 5,000 lbs/hr for each engine.

All you need is collected, though not published, in airlines' Flight Data Monitoring (FDM).
Airlines collect a load of parameters for training and statistical purposes. If you can contact an airline, tell them what you're doing and make it sound like you could improve fuel economy, there's a good chance you can get some of the data.
Another place to seek would be aircraft manufacturers like Boeing or Airbus.


text:
Is there a regulation that requires manufacturers to cover AD's for the life of the equipment?
I'm usually pretty good at finding regulations, but I can't find anything in this regard. I'm curious if manufacturers such as Cessna, Piper, or even Lycoming and Continental are required by law/regulation to cover parts and labor for any airworthiness directives (AD) for the life of the equipment.
For example my 1977 Cessna 177 Cardinal II recently got an AD that required a significant amount of labor to complete (16 hours I believe). This AD was covered entirely by Cessna at their expense. This isn't the first AD that I've had like this, but it surprises me that a nearly 45 year old aircraft is still being covered by the manufacturer.
Is there a regulation that requires this for certified equipment?

Which AD is that?   The only recent one I saw was to check for a certain muffler manufacturer. 1973 Cessna 177B (fixed gear).

@CrossRoads I think this was for the inspection of the stabilator hinge assembly, which required removal, disassembly, and reassembly/installation of the entire rear stabilator (recently I mean this was probably 2 years ago). The most recent one I got was an AD for the prop (can't remember if it was the pitch mechanism or the prop bolts), but it was also covered by Cessna.

There must be a better way to find them.  I used the link in the answer below, and searched on Cessna and filtered for 177, and only got a short list back  https://www.faa.gov/regulations_policies/airworthiness_directives/search/?q=cessna&makeModel=&type=Current&sort=effectiveDate&direction=desc&filter=177  Nothing showing in the last 2 years, and I know the muffler AD was just released in the last couple of months, the shop showed me their copy of it.  I had my propeller blades replaced in November for failing the width inspection, but that was just regular wear & tear.

The answer is basically no for aircraft not under warranty, but...
I've participated in numerous AD related activities on the OEM side, and I've never seen an AD with a commercial policy incorporated into it that dictated who pays for compliance, kits, or labor.
So strictly speaking, the aircraft operator is on the hook once an aircraft is out of warranty, but the OEM will normally have an internal commercial policy in place that its program office, customer support organization and spares organization uses as guidance on charges.
There is usually a Service Bulletin with a kit that has to be incorporated to terminate an AD and the OEM will decide whether to make the SB and kit available free of charge for some period of time when it's required to comply with an AD, for reasons of morality, politics and marketing. The commercial terms will be included in the Service Bulletin.
That is probably typical, but if an OEM is in a financially tight position and an AD's compliance is really expensive, the OEM may decide to make the operators pay for the SB and kit, or the costs related to a repetitive inspection, and take the heat by getting yelled at during operator conferences.
And sometimes, as in your case, if labor is significant, the OEM may also include a labor charge-back policy that will refund labor costs based on the estimated man-hours quoted in the Service Bulletin.
Sometimes operators include out-of-warranty "AD clauses" in their purchase contracts to avoid getting burned. And sometimes operators, especially those that may be looking for more aircraft, cut their own deals on the side.
Another factor is that, in order to get less onerous compliance terms or limitations in the AD itself (as I suspect in your case), the OEM may convince the regulator that they plan to proactively "campaign" a mod free of charge including labor charge backs, with a campaign completion date, and which may even include sending out dedicated teams to do the work (as with the Cardinal stabilator slot mod).  Sometimes this is enough to avoid an AD being issued at all if the regulator is satisfied that every affected aircraft will be fixed by a certain date.

As far as I know there is no legislation that requires a manufacturer to cover the cost of an AD. However its within their interest to do so. Keeping you in your Cessna buying parts when you need them and generally being a free advert on every airfield you land at may be worth more to the company than the cost of fixing an issue the FAA says in pretty serious.
The recent wing spar AD proposal on most PA-28's has caused some uproar that is a good example of the counter case. The AD proposal even goes as far as to estimate the cost on US operators, thats you the owner not Piper.
If you select some random AD's from the FAA's recent listings they all use the same verbiage "cost on US operator" implying that the FAA assumes the owner/operator of the aircraft will be the one on the hook. Sometimes that means an 255 dollar part and sometimes that means a 3 Million dollar fix


text:
When evacuating after a rejected takeoff, what is the minimum distance you should be from the plane and which direction should you run?
In case of a rejected takeoff, and due to a malfunction or engine explosion, how far do you have to distance yourself from the plane and in which direction would you run towards?
In my opinion (please correct me if im wrong) this is what i think, for direction, the most logical sense would be upwind incase of engine fire. for distance, during our training we were told 1 wing span...?
Please include some official references like FCOM, FCTM or other similar documents!
Thank you for taking the time to read my question too!

"in which direction would you run?" I'm pretty sure "away from the plane" is the most important part, and anything else is secondary.

You should run upwind if you had to make a decision.

"...during our training we were told 1 wing span..."  That sounds like an answer to me.  Are you just looking for a second opinion?

If I were in the situation, I doubt I'd stop at the minimum distance that somebody on the internet says is safe.

Which direction? Uphill and upwind. How far? A hell of a lot farther than a wingspan. Burning things like planes, cars, etc. are full of sealed containers with liquids in them. When liquids in a sealed container are heated by fire, they have a bad habit of producing BLEVEs.

In most rejected takeoff scenarios, an evacuation (especially a passenger-initiated evacuation) will cause far more harm than remaining seated.  Let the pilots, who know things like aircraft weight & speed at abort & presence/absence of fire warnings, plus comm with eyes outside the aircraft (the control tower) make that decision, then FOLLOW THEIR DIRECTIONS. And for goodness sake, don't take luggage with you.

First and foremost, you follow the directions of the flight crew and any emergency services you encounter. This takes precedent over anything anyone else tells you. Failing to do so may put your life and the lives of those around you in danger.
That said, lets break this down into the possible sources of danger...
Brakes and Wheels
If you're evacuating from an aircraft there's fair chance the brakes and wheels are extremely hot and possibly overheating. If that's the case there is a danger of them exploding. We have a good answer about how firefighters deal with these, which says to avoid being directly in line with the front or sides of wheels and to prefer being at a 45° angle to them.
Based on this, you should avoid being close to tires in general and ideally keep to a path that puts you at 45° to the wheels until you are at least 80 m away (263 ft). The most important thing is to avoid being directly inline or to the side of the tire.

Engines
The engines are normally shutdown asap after an emergency landing, however they could still be running. If the engine has been shutdown and isn't on fire it should pose no threat to your safety, though for good measure I'd avoid putting myself in line with the turbines (or generally to the side of the engine), because if they break/explode it will not be contained.
If an engine is still running, on an airliner you'd normally avoid evacuating on that side of the aircraft as there is a danger of being sucked into the front of a running engine or being hit with the hot air coming out the rear. Again I'd avoid being to the side of the engine in case of turbine disc failure.

Fire and Smoke
Fire and smoke can be spread by the wind, so as others have said, I'd prefer to be upwind to avoid a lung full of toxic smoke and being in the path of a fire. Though I think this is very much a secondary consideration. I'd be much more worried about the tires.
Explosions
If there is a general explosion on the aircraft debris could fly in any direction so there is no preference for a safe direction to run in this case. For distance I'd suggest an absolute minimum of the 80 m as per the brakes, but why would you want to be closer than necessary to a potential explosion? Keep going and DO NOT stop to take a selfie or video until you come across some emergency services, who should guide you to a safe location.

One rule of thumb that firefighters are taught is that the 'safe' distance for the public to be from a fire is when it appears about the same size as your hand at arm's length.

That might be helpful if the entire plane is already on fire, but when there is only a wheel fire this is certainly not far enough away.

@Bianfable depends if you take 'it' to be the fire or the aircraft. Robin can you clarify?


text:
Why can't pilots drink alcohol after a flight?
Why are pilots told not to drink alcoholic drinks even after landing, even when their next flight is more than 24 hours later?
Is this some kind of precautionary rule?

Are they told not to drink after a flight? There's 24 hours between bottle and throttle, but I haven't heard of any time between throttle and bottle, except if you are driving home from the airport.

The only reason I can think of is that (airline) pilots should not drink at the airport while in uniform as it gives kind of a bad impression.

@DeltaLima Okay . That might be the reason then . Maybe they are allowed after reaching back home . Thanks.

Do you have a source or anything where you got this from so that we can get the context figured out?

I'm fairly confident it's the "No drinking in uniform" rule that many airlines enforce: it would make some passengers nervous to see pilots in the bar drinking, as they have no way of knowing which pilots are newly arrived and which are about to depart.

Could there be a concern about pilots being tested for alcohol, and they wouldn't be able to tell if the drinking was on or off duty?

@fooot I'd assume that alcohol tests would only occur when on duty. Regardless of whether the drinking happens on duty or not, you darn well better be sober by the time you report for duty.

Commercial pilots (in the United States) are usually not allowed to drink while on duty regardless of their flight status because, among other things, it would be frightening to any prospective passengers who might see them drinking. For example, American Airlines strictly forbids consuming alcohol or any intoxicant publicly while in uniform. Here is the exact text of their company policy:

Rule 25
Unauthorized possession or using any intoxicants on Company premises
  at any time, or drinking intoxicants in public while wearing a uniform
  with Company emblem or insignia is prohibited.

Note that this does not disallow drinking as long as it is (1) not on company premises, and (2) is in private. Obviously, if the person is a US crewmember then they must adhere to FAA rules in addition to company rules (see FAR Section 91.17 for details on those rules).

Pilots absolutely can drink after a flight once off duty, just not in uniform.  Every company I'm aware of prohibits alcohol consumption in uniform while in view of the public.  This prohibition is about maintaining an image and to not associate drunk pilots with the airline.  The regulations have no verbiage about uniforms but stipulate no one on-duty may consume alcohol.
The rules for air carrier pilots is laid out in 14 CFR 120.37 (excerpt):

(b) Alcohol concentration. No covered employee shall report for duty or remain on duty requiring the performance of safety-sensitive functions while having an alcohol concentration of 0.04 or greater. No certificate holder having actual knowledge that an employee has an alcohol concentration of 0.04 or greater shall permit the employee to perform or continue to perform safety-sensitive functions.
(c) On-duty use. No covered employee shall use alcohol while performing safety-sensitive functions. No certificate holder having actual knowledge that a covered employee is using alcohol while performing safety-sensitive functions shall permit the employee to perform or continue to perform safety-sensitive functions.
(d) Pre-duty use. (1) No covered employee shall perform flight crewmember or flight attendant duties within 8 hours after using alcohol. No certificate holder having actual knowledge that such an employee has used alcohol within 8 hours shall permit the employee to perform or continue to perform the specified duties.

The rule here is 8 hours "bottle to throttle" and at the end of those 8 hours for BAC must be less than 0.04.
14 CFR part 121 Appendix J further stipulates that pilots may not perform "safety sensitive" functions until BAC is below 0.02.  Additionally, many company operating manuals (FAA approved) require 12 hours between alcohol consumption and the beginning of a duty period.
For most pilots, the rule is 12 hours "bottle to throttle" and BAC < 0.02.  This means a pilot, once off-duty and out of uniform, can enjoy a drink as long as the overnight is longer than 12 hours.

authors: Эдуард Савушкин


text:
What radios are airliners / large aircraft equipped with?
I know that pilots have to talk to the tower over the radio, and apparently you have to tune the radio to the right tower frequency. I've also heard that in an emergency, you're supposed to "squawk 7700." Presumably you're not just making bird noises with your mouth, but some sort of radio code. Are these the same radio system? What radio communication systems are modern big jets equipped with?

Numbering the radios that I can think of offhand in the old 747-100 and -200 aircraft that I used to fly produces:

2 VHF voice communications radios.
2 VHF navigation radio receivers for receiving VOR and LOC signals. The LOC frequencies are paired with UHF frequencies for receiving glideslope signals.
1 ADF (automatic direction finding) receiver.
1 HF (high frequency) voice communication radio.
2 transponders to send whatever the "squawk" is when interrogated. #1 was used on odd days of the month, #2 on even days. There are a number of standard codes, but ATC assigns a 4-digit code to each aircraft during flight under their control. There is never an 8 or a 9 in the code because it's an octal code.
1 SELCAL (selective calling) receiver, which will sound an alert if it receives a signal sent by a ground station. It may not be a separate radio but just a box listening for a tone on one of the voice communication radios.
1 weather radar, and, yes, radar is a radio (radio detection and ranging) employing both a transmitter and a receiver.
1 radar altimeter for use in the final stages of the landing approach. Some were "talkers" in that starting around 50 feet, they would announce your altitude in increments of 10 feet.
1 GPWS (ground proximity warning system). I'm not sure whether it and the radar altimeter shared a box/circuitry/antenaes.
1 GPS receiver, which we got only in the last few months before I retired in 1999
1 ELT (emergency locator transmitter)
life raft locator beacons. I can't remember how many life rafts there were.
life raft voice communication on 121.5 and maybe 243.0.

I may not have remembered them all.
Modern transport category aircraft would also have SATCOM. Military aircraft would have UHF voice communications and mission appropriate weaponry radios.

Modern aircraft would also have data HF and SAT links used by ACARS.

Thanks for the detailed answer! Could you clarify what the two navigation radio receivers were for? Are those the radios that look for the navigation beacons on the ground?

the black boxes' locator beacons are technically audio devices (they ping in the supersonic range underwater).

@ratchetfreak If the black boxes come to rest on land (not underwater), are these audio devices detectable?

@raptortech97 That which is typically referred to as a navigation beacon on the ground would be an NDB (non-directional beacon). An NDB normally transmits its signal continuously and can be received on board an aircraft by the ADF when tuned to the frequency of the NDB. I'll revise my answer to give you the info you want about the two navigation radio receivers.

Passenger cabin pay phones?

Terry, usually aircraft are equipped with 2 ATC transponders, I assume the B741 / B742  had two as well? One active and one standby to replace the other in case of failure, usually alternated between flights. The transponder transmits the squawk code to the radar (Mode A), as well as altitude (Mode C). In Mode S, squawk code, altitude, flight id (callsign) and more data is transmitted by the transponder. It also replies to TCAS interrogations. You could add a TCAS interrogator to the list as well.

@DeltaLima I had completely forgotten about alternating usage of the 2 transponders until I saw your comment. Good catch! I edited my answer to conform.

No UHF radios on board?

@Koyovis Not for voice communication, only the DME frequencies. One would think that there would be occasional trouble going into military fields without UHF voice, but I never ran into that.

This site has good information about the various radios on the 737 classic vs. NG, which will be similar to other modern airliners (though locations may differ somewhat). The graphics at the bottom show the external antennas, which include (for the NG):

Glide Slope - for ILS guidance
Localizer - for ILS guidance
Weather Radar
GPS
Radio Altimeter
ADF 1 - Navigation
ADF 2
Marker Beacon - for approach guidance
DME - Navigation
VOR - Navigation
TCAS x2
ATC 1 - Maybe transponder, ACARS
ATC 2
VHF 1 - Regular voice communication
VHF 2
HF - For long range voice communication, such as oceanic crossings
ELT - Emergency Locator Transmittor

Please note that the above location diagrams are only a guide as the antenna fitted depends upon the customer avionics options. Eg some NG's do not have ADF but do have SATCOM or IFTS/Airphone.

More and more planes have satellite antennas for in-flight internet access, too. Military planes will also include more antennas for things like UHF and SATCOM.
Another site offers some details about certain radios on the 737 NG, including the power each one uses:
HF Voice Transceiver        400W
VHF Voice Transceiver       25W
DME (962 to 1150 MHz Xmit)  316W
Radar Altimeter (4300 MHz)  400mW
TCAS                        400W
Transponder (1090 MHz)      631W
WX Radar (9.3 Ghz)          120W

For instance, it's interesting how the HF radio uses much more power than the VHF radio, and that the transponder uses the most power on the list.

Those power ratings are surely not what each device “uses” from the electrical bus, but rather the RF transmit power. A transponder isn’t going to draw 600W constantly - it’s emitting that for on the order of a few milliseconds for every few seconds that it’s on.


text:
Are drones used in firefighting, agriculture and pest control?
Well, as the question says I am interested in the use of drones in agriculture.
Are there any drones designed to carry a tank of some chemical or water?
How large are those tanks?
I have seen that airplanes are used in agriculture and in extinguishing forest fires. They can carry tanks containing 500-2000 kg (or more) of chemicals/water.

Here's an article that claims Japanese farms have used drones for crop dusting,unfortunately it gives no references: http://modernfarmer.com/2013/07/drones-drones-on-the-range/

Probably this one, though it's not autonomous.

These guys seem to offer some products in that space however it seems many of them are of the remote control variant (not fully automated). Crop dusting is a pretty routine task and you could easily program a drone to cover a specific field at a given time and let it do its thing. The main issue you will face in the current market is simply useful load. Ignoring the military drones out there most of the commercially available unmanned vehicles are on the smaller side and simply don't have the useful load of something like a Piper Pawnee that is used for current crop dusting.
It does seem that the FAA has approved some drones for this use but that was recently so Im sure it will be a little while before we see them. Although it seems Japan has been using them for this purpose for some time.
So yes tank carrying drones do exist (but I cant find the volume of the tanks, they do however appear pretty small).

FWIW any small drone could be modified to carry a tank and spraying device provided it could lift it. All things considered people have built some pretty big RC planes

Under current regulations you can't operate a drone without operator who has it in sight anyway. You can program it to do the task on its own, but somebody will still have to be there watching it and prepared to take over controls in case the automatic fails.

I once worked in the UAV company, which was contracted to supply a system to identify trees. To achieve this, all you need is a good camera and an image recognition software (now to be easily written using .NET).
I have not heard about drones carrying such large amounts of chemicals, so sorry about that. In this part of the world (eastern Europe) we have enough of our own, conventional planes which do the job just fine (like PZL-106 Kruk). I guess buying drones to do that would not be economical (again I'm just speaking for my country)

I am not an expert, but i have seen a few times Octocopter being used in agriculture industry. To carry a thanks of chemical or maybe for watering down purposes, it need 8 rotors to make it more stable. But it is depend on how large the farm or the area you want the drones to be utilized.
I have seen some farmers will custom or attached something like arm to drones. It depend on the load that specific need to carry or how you want to use it. Hexacopter or maybe quadcopter if only for simple task or experiment. But to see Octocopter do the job is normal for me. Seen dozen of times.


text:
Do airports use automated ground operation systems?
I'm interested to know if any airports use an automated ground operation system guide planes between gates and vise/versa from/to landing strips/tarmacs.

I feel like there is a dupe hanging around somewhere but can't seem to find it

The last sentence of your question really turns this into a shopping question, which is explicitly off-topic here. I also do not believe that there is any automatic guidance system in use today, unless you are talking about taxiway lighting systems that help a pilot?

Possible duplicate of Is it true an ILS CAT IIIc can automatically taxi-in an aircraft?

Nope, ground movements are what the railroads call "dark territory". shudder

Advance Surface Movement Guidance & Control Systems (ASMGCS) in different levels are being used for this purpose.  Many airport in the world uses the concept of Follow Green, where the aircraft is supposed to follow the green taxiway centre line lights to reach the parking stand after vacating runway and vice versa.  Surface Movement Radars combined with MLATs aid for these purpose.
You can find more information on this from ICAO Doc 9830.

There is nothing (as far as I know) thats currently in place to guide planes on the ground. Some airports are equipped with ASDE-X systems which allow the tower to monitor ground movements closely (and potentially if they are out of sight) but the system does not offer any progressive guidance capabilities. Take a look at the question @Pondlife has linked in the comments for some more interesting info on how this has been a limiting factor in cat IIIc approaches.


text:
How well can an airplane which is tied down be protected from a blizzard?
I've been in the very early stages of shopping for my first single engine plane. That has made me more thoughtful about the environment in which a given plane is stored. So the recent blizzard in the Northeast has had me asking some "what-ifs" from a perspective buyer's point of view.
In the Boston area, there are forecasts for 15-25 inches of snow. If a typical GA plane (e.g. a C172) is tied down in those conditions, is the weight of that much snow on the wings sufficient to cause any permanent deformation or other issues? Are there things you would instruct your pre-buy inspector to pay extra close attention to knowing the plane had been through such an extreme event?

The largest snow storm I've been through(while at an airport) was about 1 foot. At that weight, the issue I saw was some aircraft tipping onto their tail.

There are several additional measures which can be done to prevent a tied down airplane from harsh weather, storms and blizzards. However, nature is always more powerful than humans and  it can overcome any safety measures taken by them.
If your airplane is tied down properly and securely, hail is a bigger threat than storms or blizzards. A hangar protects an airplane more than the one outside, but it costs a lot more.
This article (and page 2) discusses several measures you can take to protect your airplane against harsh weather. To avoid redundancy, I am just pointing (and paraphrasing) a few here:

Parking spot
  If you can, choose a spot which can break the wind intensity.
Anchor points
  Depending on the aircraft, the anchor points' holding strength must be 3000-4000 lbs.
Ropes
  You should use those ropes which do not shrink when wet (e.g., nylon or dracon ropes instead of Manila).
Position
  If possible, park aircraft nearly into the wind as possible.
Weight
  A lighter object is easier to get displaced. You can fill-up the tanks to add extra weight.

If you interested in reading some long articles, this and this provide some useful information too.

Regarding your second question about snow on the wings, I hardly doubt that something like this will happen:

The above happened because:

... when the tail hook was torn off and the plane was pushed forward, breaking the spar. (picture here)

Airplane wings are very sturdy. They can bear the weight of a foot or two of snow.

" I hardly doubt that something like this will happen" means that you have minimal doubt that it will happen.

Our club found that with a good quantity of combined ice/snow (I don't remember how much) our Cessna 172 tipped onto the tail.  The Piper Warrior did not for whatever reason.  Perhaps wise to add some weight forward of the main gear when parked out in those conditions.
The only damage caused on the Cessna (there was none on the Piper) was a broken tailcone as the airplane had the misfortune to have the tailcone snag the edge of the tire tiedown point marker as it tipped back...  If the airplane had not been parked straight, it looks like it just would have been sitting on the rear tie-down hook instead (as a side note, it's common to see scraped tie-down hooks on flight school airplanes from excessive tail-down attitude during takeoff/landing, yet the tailcones don't ever seem to get damaged) and the tailcone would have survived.

One foot of snow would be roughly equal to 1 inch of rain.
The 172 has 174 square feet of wing area or 25,056 square inches.
25056 inches$^2$ × 1 inch/231 inches$^3$/gallon = 108 gallons of water
108 gallons × 8.3 lbs/gallon = 900 lbs.
2 feet of snow would be 1800 lbs.  As the Cessna 172 weighs at least 1800 lbs (empty), even 2 feet would be within the negative G limit of around - 1.5 Gs.
As mentioned by others, good tie down ropes are in order, and a tail brace can help keep it on all 3 wheels.  Another option is to fly it to a safer location and allow the storm to pass.
The aircraft manufacturer may have addition information for a particular make or model.

Requires a wing pressure difference of only 1/10 psi to fly!

I feel that many times there is hidden damage to airplane. The extra weight pushing down on attachment bolts. When flying the wing lifts that stress. You have extra weight pushing down.  I now have 9 inches of snow on my 73 Piper Cherokee (January 7, 2022) at New Haven, CT. I will remove all snow/weight asap.


text:
Is there a particular reason that EasyJet uses U2 as their code?
Does anyone know why EasyJet uses U2 as the prefix for flight numbers? Other airlines have more logical prefixes. Eg. KL -> KLM, AZ -> Alitalia, BA-> British Airways, etc. Even though they do not always match the airline name exactly, they do mimic the name.

EZY (EasyJet UK) code and EZS (EasyJet Switzerland)are the ICAO codes, whereas U2 is the code generated by IATA for them when they applied for an IATA code.
http://www.easyjet.com/ejcms/cache/medialibrary/files/travel%20agent%20online%20guides/en/amadeus
EasyJet Airline Company Limited (UK Based) - (IATA code: U2; ICAO code: EZY; Callsign: Easy)
EasyJet Switzerland SA (IATA code: DS; ICAO code: EZS; Callsign: TOPSWISS)
ICAO codes are used for operational purposes like flight planning, ATC, etc. IATA codes like U2 are generally used in timetables, reservation systems, departure/arrival information, etc. - in other words information that is meant for the general public.

Easyjet got their IATA code fairly late on, and as such could not use EZ (which was in use by Sun Air), so they were randomly issued their IATA code of U2.
They do have the three letter code of EZY, just as British Airways has BAW as well as BA.

The 2 letter IATA code is the airline code.  The flight callsign is the 3 letter code so Easyjet callsigns are "EZY321", pronounced "Easy 3-2-1".

The three letter code is the ICAO designation, and airlines are free to use either their two letter code or three letter code for call signs.  British Airways uses "Speed Bird 123" as their call sign for most flights, and BA123 for the flight number.

I think you are wrong.  Can you give any example of the the IATA code being using in a call sign?

@Moo, the call sign is written using the ICAO code on the flight plan, because flight plans are governed by ICAO. The spoken form uses a radiotelephony designator instead, which may not be related to either the code nor the airline name, as evidenced by BA's "Speedbird" and former PanAm's "Clipper". Note, that the call sign usually is the flight number, but not always. You can have flight BA123 with call sign BAW55B, which would then be spoken as "speedbird five five bravo". Also don't forget that these days most flights have more then one flight number due to code-sharing.


text:
How does a flight control computer deal with control surface disengagement?
What action does the flight control computer take (under normal law) when it realizes, for instance,

Inboard actuator of aileron/elevator disengaged or
There is a disconnect between the LVDT and the actuator

Is there any backup for this?
Are there any minimum control requirements established for the flight control computer to 'arm' or 'enable' the "backup" if available ?

What do you mean by "disengaged"? Do you mean the actuator physically does not connect to the control surface anymore? Are you assuming that the control surfaces are electrically actuated?

@RonBeyer I think he is talking about a  disconnection of the hydraulic  controller for the hydraulic actuator (which is controlled electronically in FBW) or the sensor that tells the computer the actual position of the actuator. That's what I'm getting. Is that right user2927392?

Yes TomMcW, thank you. Flight control computer is reported by sensors that the actuator is disengaged.

Well the A320 and A340 have 2 actuators per deflection surface (in case of elevator or aileron, spoilers do not have 2 actuators per 1 surface).
If one of these actuators fail, as in they have no pressure supplied to them by either hydraulic power systems (Blue,Green,Yellow) the other actuator which is supplied by a different pressure supply system (to avoid a single point failure) will take control of the of the surface. The flight control computer would continue working under normal law given that the other 2 Primary flight computers (PFC) are working properly. However, if the secondary flight computers(SFC) take control (after at least 2 failed PFCs), the aircraft would lose the ability of flight with normal law and thus direct law would be activated.
A disconnection between LVDT and a deflection surface would cause a disruption of the feedback towards the PFC. The PFC will notice that it is sending signals but receiving no change in feedback and will consider itself out of order. This would mean the respective PFC will render itself in a passive state and pass control to the other PFC connected to its own actuator. Depending on whether a PFC or an SFC in control, you would have either normal (at least PFCs intact) or direct law (the 2 SFCs are in command)
A Mechanical backup is available in the form THS(Trimmable Horizontal Stabilizer) which is activated by the trim wheel and the rudder which is available through the pedals for the A320 and A340.


text:
Can I count simulator hours towards a commercial flight certificate training?
I attend a Part 141 training school and have a total of 98.5 hours of flight training towards a commercial certificate, with 8 hours of simulator training, also for the commercial certificate. Can I count both the flight and the sim hours towards the aeronautical experience for the commercial certificate? It would be a lot cheaper and faster to reach the required 120 hours this way. The Beech Baron is not cheap to rent!

Somewhat related : http://aviation.stackexchange.com/questions/1780/does-simulator-time-count-as-time-in-type and http://aviation.stackexchange.com/questions/1768/how-should-simulator-time-be-logged-in-a-pilot-logbook

According to the FAA, yes you can count those hours, but they can only count for only

Under FAR part 141:
7 hours(35%) of 35 hours of flight training towards a private pilot certificate
17 hours(50%) of 35 hours of flight training towards an instrument rating
36 hours(30%) of 120 hours of flight training towards a commercial pilot certificate
10.5 hours(30%) of 25 hours of flight training towards a multi-engine rating
12.5 hours(50%) of 25 hours of flight training towards an ATP cerfificate
2.5 hours(10%) of 25 hours of flight training towards a flight instructor certificate
1.5 hours(10%) of 15 hours of flight training towards an instrument flight instructor rating.

From http://www.dctaviation.com/#!sim-faq/ccj4
From what I see, you can probably fill up your remaining hours with sim time because you only have a little over 20 hours left and you can have 28 more hours of sim time towards your certification.

You can count the hours for certification subject to certain limiations. According to Federal regulations, Title 14 → Chapter I → Subchapter H →Appendix D to Part 141—Commercial Pilot Certification Course,

(2) Training in a flight simulator that meets the requirements of §141.41(a) of this part may be credited for a maximum of 30 percent of the total flight training hour requirements of the approved course, or of this section, whichever is less.

As the commercial pilot certificate requires 120 hours of flight training, this works out to 36 hours.
The simulators should be approved by the administrator. According to §141.41   Flight simulators, flight training devices, and training aids,

(a) Flight simulators. Each flight simulator used to obtain flight training credit allowed for flight simulators in an approved pilot training course curriculum must—
(1) Be a full-size aircraft cockpit replica of a specific type of aircraft, or make, model, and series of aircraft;
(2) Include the hardware and software necessary to represent the aircraft in ground operations and flight operations;
(3) Use a force cueing system that provides cues at least equivalent to those cues provided by a 3 degree freedom of motion system;
(4) Use a visual system that provides at least a 45-degree horizontal field of view and a 30-degree vertical field of view simultaneously for each pilot; and
(5) Have been evaluated, qualified, and approved by the Administrator.

For other certification courses, the percentage of simulator time that can be credited vary. For Instrument Rating Course, it is 50%, while for Private Pilot Certification Course, it is 20%.


text:
Which airport is featured in this Delta commercial?
I just saw a Delta commercial with a plane taking off from a runway with a 16R designation (thus, the plane in the commercial was departing from 34L). Does anyone know where this airport is? Climbing out, there appears to be a large body of water ahead, if that helps!

I had always heard that Van Nuys (KVNY) was the only airport with a 16R/16L runway designation, but the airport in the video isn't Van Nuys.

Can you provide a link to a video of the commercial, that may help shed more light on the situation.

There are many airports with 16L/16R, here's another example.  Sydney, Narita, Van Nuys.  As reirab points out, there are only 18 possible numbers so this is not surprising.

Based on @reirab's answer, the same perspective from Google Maps.

@reirab is 100% correct, it's Paine Field / Snohomish County International. Source: I am based there, and that's a piece of the Everett Boeing plant on the right side. :) You can see Hat/Guemes Island and a piece of Camano Island, as mentioned, and the lights of Everett at the far top right.

Thanks so much! I've actually had a VIP tour of that Boeing facility because a friend of mine is an engineer there. I flew up in my C-172, but now can't recall which airport I landed at! If I remember correctly, it was a small GA airport ...

It's Paine Field (KPAE) in Seattle. It has both 16L and 16R and has water (the Puget Sound) directly ahead if you're taking off from the 34s. 34L is also the only runway there large enough for most jet traffic, so that's what a Delta jet would be using if it were there.
It's also worth noting that this commercial is about flight testing and Paine Field just so happens to be the home of an aircraft production facility for some little company named 'Boeing.' You can see their Everett Production Facility on the North side of the airport in the Google Earth view and the aerial photo below. Interesting fact: that facility, originally built in 1967 to produce the Boeing 747, remains the largest building in the world by volume even to today. It's 79% larger than the next largest building and a full 3.63 times the size of NASA's Vehicle Assembly Building, the previous largest building in the world by volume, where NASA performed final integration of the Saturn V and Space Shuttle stacks and where it will do so for the SLS.
Here's the Google Earth view, and it looks like the two islands on the left in the commercial are Hat Island and Camano Island:

Sectional Chart Showing KPAE

Aerial View of Paine Field - Source: Wikipedia

Honestly, the claim of there only being 1 airport with any given runway number seems rather suspicious, since there are only 18 possibilities. Granted, the requirement of having parallel runways makes it a little less unlikely, but still many (if not most) large airports have parallel runways.

And with many areas having prevailing winds out of the North East or South West, a 16/32 runway setup seems likely to be fairly common.

@JonStory Did you really mean to say 16/32. I suspect that's a typo. Also on the U.S. west coast a 16/34 runway is a true north-south runway due to the the magnetic variation of appoximately 20E.

I meant 16/34 as British runways don't use 320 degree circles :p it was indeed a typo. In much of the world 16/34 would be northeast/southwest to some degree

@JonStory With no magnetic declination, heading 340 would be Northwest, not Northeast. With the declination on the U.S. east coast, Paine's 16-34 runways are actually almost exactly North-South (179/359 true heading.)

Thanks everyone for your input and answers! When I said "there was only one airport with 16R/16L designation," I should have clarified that that was in the USA. There is a film about Van Nuys airport called "16 Right," and it tells about the history of KVNY. Perhaps they said it was the only GA airport with twin runways of that designation, and I misheard!  Hmmm... Now I'll have to watch it again!

@Spencer Even in just the USA, it seems a little dubious. There are over nineteen thousand airports in the USA alone (with 18,762 of those being GA as of last year's data from the Bureau of Transportation Statistics .)

Thanks Reirab!  Those stats alone are great "factoids!"  I totally agree it sounds dubious given those numbers, but then again most GA airports aren't really busy enough to justify parallel runways, so maybe it is factual, if you consider just GA in the USA. I'm certainly curious now about the truth, but I really do appreciate your feedback!

@Spencer You're welcome! Just from a quick search KHEF is another (98%) GA example with a 16-34 L/R runway configuration. It's about 20 miles WSW of D.C. There were a few others I noticed that had mostly GA traffic, but also some commercial and/or military traffic, like this one in Fort Worth and this one in Eugene, Oregon.

Awesome! Thanks again! You've put far more effort into it than I would've expected, but it's appreciated! I'm going to have to watch that damn movie again (16-Right)... Hmmmmm

You can find the full list of runway data for the US here (as provided by the FAA)
They list (confirmed on google maps to see whats actually painted on the tarmac)

DEN (Denver)
SEA (Seattle-Tacome)

There may be others as well you can check the list for a more complete overview.

In addition, Eugene Airport in Oregon also has 16R/16L runways. Outside USA, at least the two airport in Tokyo (Haneda & Narita), Sydney, as well as Roma Fiumicino have the designation.


text:
What kind of ADS-B identification code is FFxxxx, where xxxx are numbers i.e. FF0024?
I live near an airbase and use an ADS-B receiver that picks up aircraft using regular ICAO assignments. They do not include flight path details or position info, but can be identified by the ICAO number which is a civilian aircraft identifier. Sometimes, it captures aircraft SSR returns with what appear to be invalid numbers, beginning with FF followed by 4 digits, such as FF0024 FF7777.
Are these drones? cruise missiles? Aurora? Or some other military aircraft identity?

What receiver do you use? What software do you use?

I am going to assume you use Flightaware's variety of dump1090 as a decoder.
When that receives a Mode A code, it publishes it as if it were a 24 bit address. The first two hexadecimal digits are filled with 'FF'. I have no idea why this may be a good plan.
In mode_ac.c, lines 368-370:
// Fudge an ICAO address based on Mode A (remove the Ident bit)
// Use an upper address byte of FF, since this is ICAO unallocated
mm->addr = 0x00FF0000 | (ModeA & 0x0000FF7F);
These may be drones but most likely they are just simple aircraft replying to Mode A/C interrogations.
If you are in the USA, FF7777 is a field test transponder (Range & Azimuth Beacon Monitor, RABM) , usually located not far from a radar to verify the correct working of the radar.

If these are 24-bit ICAO aircraft addresses, then they belong to an unallocated part of the address space. Several places on the net (1, 2) document that addresses starting with F are reserved for future use by ICAO.
The referenced documents, however, pre-date the widespread development and deployment of UAVs, and other sources on the net (e.g. here, here) indicate that "high-order" 24-bit addresses (which apparently means ones starting with F) are to be used for UAVs equipped with "ACAS Xu", a collision avoidance system (currently under development? testing?) which uses the same ADS-B compatible radio protocol as ordinary ACAS/TCAS systems, but cannot send interrogations.
The point of using addresses starting with F (rather than allocating addresses out of the nationally assigned range for the drone's country of origin) seems to be that the ACAS protocol uses "which aircraft has the higher address" as one of the inputs in coordinating which resolution advisory to issue. If a drone and an ordinary ACAS II equipped aircraft are converging, there's a risk that both ACAS systems would issue "climb" advisories (or both would issue "descend") and be technically unable to change it unless the drone has a higher address. At least, that's what I get from the sources linked above.
So your FFxxxx traffic, if you're sure they are 24-bit addresses, are probably drones exchanging ACAS reports with nearby aircraft. (DeltaLima's answer looks more convincing.)

ACAS X is the new generation of TCAS http://www.skybrary.aero/index.php/ACAS_X. ACAS Xu is the UAV variation. I assume it has no interrogation capabilities to prevent foes from detecting its position and shooting it down.

@rbp not every UAV is military. Originally Xu was thought to be entirely passive, now interrogation capabilities have been added to the scope.

@DeltaLima i will further assume that interrogation got added to the scope as more civilian UAVs took to the skies. i'm sure the ones circling war zones will have interrogation turned off.

@rbp That's correct; if capable of interrogating, military UAV will have interrogation off in war zones, but active while operating in civil airspace.


text:
How can a helicopter be designed without a tail rotor?
How will the main rotor torque be balanced if a helicopter doesn't have a tail rotor?

The vertical stabilizer usually provides enough torque balance at cruise speed - it will keep you straight if you lose the tail rotor in flight. Landing will be exciting, esp. if you have skids and not wheels.

@paul What if i use two rotors one below the other, rotating in opposite directions and without any vertical stabilization and tail rotor. What then? will it fly??

@paul: Well, landing will probably have to be carried out on autorotation in which there is no net torque.

@seetharaman That's called a co-axial rotor and is in production.

@JanHudec autorotation is for landing after the engine quits. If your tail rotor and your engine fail at the same time you are probably going to have a messy ending.

@paul: Autorotation is also for landing if your tail rotor transmission fails because there is no torque. Otherwise the torque makes the helicopter spin out of control very quickly once speed is reduced.

Not all helicopters have a vertical stabilizer that is designed to counteract the torque effect in cruise so that the tail rotor doesn't really do anything in the cruise. Some helicopters will spin out of control even in the cruise if the tail rotor fails (AS332 for instance)

Great answer on tail rotor failure from an actual helicopter pilot: https://aviation.stackexchange.com/a/21290/520

The torque in a helicopter is generated by the engine driving the main rotor in one direction, which causes the fuselage to spin in the other direction. The tail rotor shaft is horizontally mounted and hence creates it own 'lift' to provide anti-torque. The pitch of the tail rotor gives directional control.
Common ways to design a helicopter without a tail rotor:
Tandem rotors : Two main rotors mounted one in front of the other. The rotor discs spin in opposite directions. All power from the engines is used for lift. Example: CH-47

Transverse rotors : Two main rotors mounted side-by-side. Example: Kamov Ka-22

Co-axial rotors : Two rotor discs are mounted one on top of the other. The engine units power both rotors. This structure requires a very complex swashplate mechanism. Example: Kamov Ka-25

Intermeshing rotors :  In this main rotor assembly, the two set rotor masts are installed at a slight angle to each other, in a transversely symmetric manner, so that the rotor blades intermesh without colliding with each other. Example: Kaman K-MAX

Tip jet : This is an interesting solution to the no-tail-rotor problem. Instead of driving the rotors with a turboshaft engine, compressed air is sent through nozzles installed at the tips of rotor blades. The engines effectively push against the air rather than the helicopter fuselage. The rotor spins just like a Catherine wheel. Example: Hiller Hornet

NOTAR : NOTAR - NO TAil Rotor uses a fan inside the boom to build a high volume of low-pressure air, which exits through two slots and creates a boundary layer flow of air along the tailboom utilizing the Coandă effect. The boundary layer changes the direction of airflow around the tailboom, creating thrust opposite the motion imparted to the fuselage by the torque effect of the main rotor. Example: MD-900

Refer to Wikipedia for more!

For unmanned vehicles, would it be practical to simply use vanes to limit the speed of rotation and then use guidance electronics which can cope with it?

Isn't the CH-47 Chinook also an example of intermeshing rotors?

@RedGrittyBrick : If you notice closely, the Chinook has its rotor discs installed at slightly different heights!
Also, the intermeshing rotors concept has the rotor masts within the same housing. This is unlike in the Chinook, where the rotor shafts are separated by a very wide distance.

@supercat : You mean, just like it is done in a fixed wing aircraft! The static and dynamic stability prevent big movements of propeller aircraft due to engine torque. But a tiny change in RPM has huge primary and secondary effects on the directional and lateral motion.
So, yes, you'd probably need very good guidance electronics for the same.

@RajDeshmukh: I was envisioning something like a design competition to build a helicopter from two rigid assemblies connected via single motor-driven shaft, which could make its way through a particular course in an area with beacons to help detect position and heading.  If a rotor is fixed at an angle slightly off vertical, having it turn faster when it's pointed in the right direction and more slowly when it isn't should allow the vehicle to make positive progress in the desired direction.

The point of the tipjet is that it's only the friction in the rotor bearing that would cause the body of the helicopter to counter-rotate? And that's presumably negligible compared wind buffetting and the air resistance of bodily rotating a helicopter so nothing much happens as long as you're not trying to hover for a long time in still air.

@Raj is entirely correct, these are all the current solutions to torque in helicopters. Each is something of a compromise. The tail rotor is very common, but uses some 15% of the engine power just to keep the helicopter straight. Tandem rotors like the CH-47 are great but give it a huge rotor area. Co-axial has a smaller foot-print, but the rotor mechanism is extremely complex and hence prone to failure.

@Raj - Yes, the Chinook's rotors are staggered in height, but they also are staggered rotationally to intermesh, because of the high dihedral of the rotors under load (as seen in your picture). Only one blade ever passes over the top of the aircraft at a time.

@supercat re: spinning things and control systems, you may find the Monocopter interesting: https://en.wikipedia.org/wiki/Monocopter#UAVs

@KorvinStarmast: True. In the strictest sense, the V-22 is a tiltrotor aircraft. I will update the answer. Thank you.

Another option to build a helicopter without a tail, is to use active flapping.
Basically the idea is to not counteract the torque of the main rotor, but use a rotor concept that does not generate a torque.
At the Technical University Delft they applied this principle to build the Ornicopter (a mix of the words helicopter and ornithopter), a tailless helicopter. Flight tests have been performed using this prototype.
According to the university:

The Active Flapping
The active flapping of blades is the key for the
Ornicopter concept. In this manner, the blade can generate a
propulsive force to rotate itself, and hence the shaft torque is not
needed. This results in a torque-less main rotor, i.e. the tail rotor
can be eliminated.

More info here

Update
Concerning the question on scalability posed in one of the comments:
I found a PhD thesis on the topic (download)  which did a feasibility study on a Bo-105 scale ornicopter. The thesis says:

"The thesis proves that the optimal design for the Ornicopter as
compared to the Bo-105 benchmark is characterized by a lower blade
loading, increased rotor tip velocity and larger vertical fin size.
This optimal design results in an enlarged flight envelope due to the
reduced rotor stall area and improved yaw stability in forward flight.
Nevertheless, despite these improvements in the Ornicopter's flight
envelope, there is a slight increase in required power when compared
with the Bo-105 specification (approximately 5% at 150 knots).
To compensate for the higher profile power needed for the Ornicopter's
optimal design, a larger rotor radius is required in order to reduce
the induced power and keep the increase in the total required power to
a minimum. This thesis may be considered as a first step in rationalizing the
expectations regarding the Ornicopter's tailless helicopter design.
The thesis proved that this new concept shows a slightly poorer
performance than that of conventional helicopters regarding power
consumption in forward flight and service ceiling. This is
disappointing since one of the assumptions was that the elimination of
the tail rotor would also eliminate the power consumption associated
with a tail rotor. "

Not that I'm aware of. The model is mainly a demonstrator. It was able to fly around freely, so perhaps it could already carry a small payload. No further effort was taken to scale it up to actually carry significant payload.

@KorvinStarmast, I added a small part concerning a feasibility study for a bigger scale

Ah, nice, improves the answer quite a bit. :)  As ever, there is no free lunch.


text:
QF-16 vs Predator
What are the major differences in between the flying of, say, a drone like the Predator, versus the QF-16? What changes so drastically in the handling of the aircraft for the remote pilot? Are the increased maximum speed and loading the only thing that makes this flight different?

I opined such because it came up in my news way too frequently than expected...

Don't let the news tell you what's good and bad. But that's a whole other topic...

USAF has been flying combat aircraft converted into target drones for decades; calling it the next big step is a few decades too late. The best possible explanation would be that the buzz was created in context of the armed UAVs being used in combat operations.
In the strictest sense, the differences in the two platforms are the same as the aircraft they are based on. QF-16 is based on a combat aircraft and as such brings to the table advantages like maneuverability, speed etc and corresponding limitations. On the other hand, the Predator (MQ-1) is based on a reconnaissance platform and brings the advantages like endurance, quietness etc. while limited by payload and speed. The handling qualities vary accordingly.
Another dimension is the use of experience gained in designing/operating QF-16 in the development of next generation combat aircraft which are expected to be optionally piloted (for e.g. the preflight tests on QF-16 are carried out by a pilot, who then exits the aircraft).

Yeah this is pretty much it: the QF-16 is a remote control F-16 and could, in theory, be used the same as a regular multi-role fighter. The Predator/Reaper/etc are much slower and are basically just a remote control plane carrying a camera and a couple of missiles. A Predator couldn't replace an F-16, but a QF-16 could replace both an F-16 or a Predator.

@JonStory Predator can "fly up to 400 nmi (460 mi; 740 km) to a target, loiter overhead for 14 hours, then return to its base." So no, QF-16 can't really replace a Predator for its intended use.

Another consideration in the difference might be latency as discussed in this question. I'm just guessing that a target drone would be flown from somewhere near the location of the exercise. As opposed to half a world away like the predator.


text:
How can I get flying again after FAA medical rejection for anxiety two years ago?
Post Military Service I was diagnosed with Generalized Anxiety Disorder and put on Zoloft (Sertraline). I had taken it for a while but had not refilled my prescription, and was off the meds with the approval of my doctor. During my FAA medical exam (3rd Class) they checked my insurance and saw that I had been prescribed the meds. I had not put it down as I misread the prompt as currently taking or being treated for those conditions.
I'm totally fine now, currently an EMT, been off the meds for 3 years now, and hoping to start flying again.
My hopes are low, but is there any hope for me getting flying again?

I doubt anyone here can answer this. You'll need the approval of an AME, and that will probably require the involvement of your regular doctor. Your case might need to be referred to the FAA and might need monitoring for a period. Lots of 'mights' and 'mays', I'm afraid. Start by taking to your regular doctor and finding a nearby AME. See what they say and take it from there.

@ReddHerring That sounds like an answer to me. Not a definite "yes" or "no", but certainly "here's the process you'll likely have to go through".

@Jim Welcome to the site and to Stack Exchange. As for "would someone require an FAA Medical to work on an Air Ambulance?", that's unrelated to the requirements for a FAA medical. It might still be on topic here or possibly on [medicalsciences.se] (I'm not familiar with their subject scope, but it sounds like it might have a chance), but it's a different question and should be posted as such. You have a much better chance of getting good answers by focusing on one specific issue per question.

Welcome to the site! As @aCVn says, the air ambulance bit is a separate question, so I’ve removed it from the post, though feel free to ask it as a separate question, I think it’s valid and on topic here. If you haven’t already done so, I’d recommend taking our [tour] and reading the [help] so you can see how the site works.

In general, as I do not have the guidance in front of me presently, if you have been diagnosed with an anxiety disorder, and later taken off the medication with no adverse effect, and the symptoms are absent, you have a high probability of obtaining a medical.
First, your primary care physician should document that you have been off the medication for x months.  Usually two years is good enough.
Then you should shop for an AME.  You want someone who is willing to work with you to get the documentation needed and submitted. Your initial application may be initially deferred, and forwarded to FAA Medical Headquarters in OKC for review. OKC has in the past taken calls on medical certification inquiries, but has also not taken them.  I would call them and ask for their guidance documentation.
If you are an AOPA member, their medical support people are excellent, and will give you specific guidance, as to what reports and findings will be most helpful.
It is possible that you might need an evaluation by a specialist, a psychiatrist, to assure that you are not walking around untreated, and do not show any signs of GAD.  GAD is often considered a long term chronic disorder, and it is not uncommon for people with GAD to have the condition for their lifetime.  In your case, you will want it to be that the diagnosis surfaced with situational circumstances, and the condition is no longer an issue, and the medication is not indicated at this time.
As a CFI, I have had quite a few primary students, and one CFI student who had similar or even more significant psychiatric disorders, and as those were addressed and they were able to drop the medications, they were again qualified for a medical.  Also keep in mind that your road to Basic Med will initially require a 3rd class or higher medical.  So it would be nice to get this administrative matter resolved.
In addition to AOPA, there are places which primarily help pro pilots, but will provide excellent services to help guide you through the process and if you are qualifying, will help you get a medical.  They can be several thousand dollars, and in your case a year of AOPA membership would be very cost effective.
As an example, I had a primary student who had a history of suicide attempts.  It turns out that she felt she was trapped in an abusive relationship.  A couple of years later the situation was different, and her PCP and therapist records were all that was needed to have the FAA issue an unrestricted medical.
For air ambulance, if you are not playing a role which requires a FAA medical, then you will not need one.  In air ambulance, the typical roles requiring a medical are pilots.  I don't know of any air ambulance outfit which requires a FAA medical for their EMTs.  You could always ask at a place that you might be interested in employment.
The FAA medical practices are in place to mitigate perceived risk.  People have situational circumstances in their life which may be outside medical issuance, but their situations also change.  To a degree, the FAA generally recognizes that.
Good luck pursuing your interests.

If you are trying to get an FAA medical because you want to work as EMT crew on an air ambulance, the FAA has no license for that and hence there is no medical certificate requirement. That said, the air ambulance company or their insurance company might have a medical checkup requirement. Ask them.
The rest of your question can only be answered by an Aviation Medical Examiner.
By the way, you can fly gliders, including ones with engines, without a medical.


text:
What is the name or part number of the Bose 'Lemo' aviation headset connector?
In a similar direction to this question, I was wondering if anyone knows the name or part number of the connector commonly featured on Bose aviation headsets such as the A20. It is commonly know as the 'Bose connector', 'lemo connector' or the '6-pin connector'.
The A20 manual merely calls it the 6 pin plug (page 13) and gives the connector dimensions (page 35).
The name 'lemo' suggests it's one of the connectors developed by the LEMO company (perhaps something from the B or K series?).

Aircraft Spruce sells the Bose 6 pin LEMO installation kit.  Have you tried calling their tech support for more info?

The connector mentioned on Sporty's is called:

6-pin LEMO Connector to GA Twin Plug Adapter (for Bose A20 Aircraft Powered Headsets)

The part number or product ID is 1643A. I'm not sure if that is Sporty's ID or LEMO as I could not find this connector on LEMO's product page.

Image Source